Real Estate: Think your property taxes are too high?

Anyone who builds a home addition or installs a swimming pool can reasonably expect their property assessment, which measures how much a house is worth and then taxes accordingly, to increase. But homeowners who think they’ve been unfairly charged have the option of filing a grievance with their town’s tax assessor’s office.

Just be sure to act quickly, because the deadline to file a grievance in New York State this year is Tuesday, May 19.

“Generally speaking, a lot of people don’t have a good impression of what their house is worth,” said Paul Henry, who has owned Tax Reduction Services in Greenport since 1990. In 2014, he said, the company helped more than 10,000 clients in Suffolk and Nassau counties file grievances in an effort to reduce their bills.

“What we do is find inequities,” Mr. Henry continued. “We look for properties that are being overvalued for the purpose of property taxes and then establish a value we think is more correct.”

Last year, 1,403 grievances were filed in Riverhead Town, said tax assessor Mason Haas. In Southold Town, that number was 1,435, according to assessor Bob Scott.

“Usually if there’s an increase in someone’s assessment it’s due to the fact that they had a building permit and maybe there was a physical improvement to the property,” Mr. Scott said. “Maybe there was a discovery that somebody may have done an addition or improvement without having a permit for it.”

Homeowners who aren’t sure whether — or by how much — a home improvement project will increase their property assessments should visit their town’s tax assessor’s office before starting any work, Mr. Scott and Mr. Haas both said.

“The thing we tell people all the time is to come in and see us first if you’re thinking of doing something to your house and you want to know if it’s going to change your assessment,” Mr. Haas said. “We’ll give you an estimate. If I can do something, I will.”

Something that won’t change a person’s property assessment is the sale of a neighboring home.

“A lot of people are under the misconception that when someone buys a house next to theirs, their assessment changes,” Mr. Haas said. “But that’s not allowed in New York State.”

If your tax bill still seems high, remember that it’s important to take town budgets into account, Mr. Henry said.

“Taxes go up every year because of inflation, essentially,” he said. “We’re paying for police departments; we’re paying for services to the schools.”

Mr. Haas added, “People come to me and say ‘My taxes have gone up.’ The first thing we see is that their assessment didn’t change, the budget did.”

If you do file a grievance, be prepared to wait for any sort of resolution.

“We have small claims from last year that we haven’t even put on the court calendar yet,” Mr. Scott said. “It’s a long process.”

For many taxpayers, Mr. Henry said, the wait is worth it.

“We have clients that save $500 and they’re delighted and we have clients that save $5,000 and maybe they’re a little more delighted,” he said.